I. Field of the Invention
The present invention relates generally to cardiopulmonary bypass systems. More particularly, the present invention is directed to an improved cardiopulmonary bypass system which consolidates and miniaturizes the entire CPB circuit on an integrated panel or box-type structure capable of being positioned within (or closely adjacent to) the sterile surgical field.
II. Discussion of the Prior Art
Cardiopulmonary bypassxe2x80x94mechanical bypass of the heart and lungsxe2x80x94is employed in both cardiovascular and cardiac surgery. A cardiopulmonary bypass circuit is composed of two primary technologies: mechanical circulation of blood during temporary heart arrest, and artificial oxygenation of blood while blood flow is excluded from the lungs. FIG. 1 illustrates a typical prior art CPB circuit 10 within a typical operating room setting. Blood is removed from the patient through use of a venous cannula 12 inserted into the inferior and superior vena cava using gravity or vacuum assisted venous drainage into a venous reservoir 14. The venous reservoir 14 often receives venous return in addition to field suction return (blood recovery via roller pump or vacuum activated suction wands). Alternatively, cell-washing technology may be employed prior to the return of blood to the patient. An arterial pump 16, typically a remote mounted roller or centrifugal style pump, pulls blood from the venous reservoir 14 and pushes the blood into an oxygenator 18. The arterial pump 16 is most often located on a heart lung machine 20, behind the main or assisting physician in the operating room, approximately 5 feet back from the patient table 21. Oxyhemoglobin is created in the oxygenator 18, most commonly through use of a porous hollow fiber capillary material with blood flowing around the fibers and oxygen flowing through the fibers. Pressure from the arterial pump 16 continues to move blood out the oxygenator 18 through an arterial filter 24. The arterial filter 24 serves as a final filter for possible air and particulate introduced through the circuit. Blood is returned to the patient via the arterial cannula 26, usually placed in the patient""s aorta.
While generally helpful in performing various cardiovascular and cardiac surgical procedures, traditional CPB circuits suffer several significant drawbacks. A major disadvantage is that such traditional CPB systems require a relatively large amount of fluid (such as saline) to prime the CPB circuit. The high prime-volume is due to the fact that the components used in traditional CPB circuits are typically quite bulky and oftentimes disposed in a spread apart or non-consolidated fashion. The use of such high amounts of priming liquid is disadvantageous in that results in hemodilution of the patient""s blood supply when the CPB circuit is coupled to the patient. Hemodilution is a paramount concern because it reduces the relative amounts of hematocrit (and hence hemoglobin) within the patient during such procedures, thereby reducing the blood""s oxygen carrying capability. This is particularly troublesome in neonatal and pediatric cases, where the amount of prime-volume is typically quite large relative to the amount of blood within the patient. To combat hemodilution, it becomes necessary to cool the patient to thereby reduce the oxygen requirements and/or introduce additional blood into the patient to raise hematocrit levels, both of which are disadvantageous to the patient. Cooling the patient is disadvantageous because it causes the patient to be xe2x80x9con pumpxe2x80x9d for the very lengthy process of cooling down and warming up the patient, which is both costly and physically taxing on the patient. Infusing additional blood into the patient is disadvantageous in that it presents the risk of contaminating the patient with blood-born pathogens (such as HIV), as well as the possibility of rejection and adding significant costs to the overall procedure.
Another significant drawback of traditional CPB circuits is that, due to their bulky size and non-consolidated layout, the individual components forming the CPB circuit are typically located at a lower vertical level than the patient. This is disadvantageous in that air emboli generated by or disposed within the CPB circuit may migrate vertically upward within the CPB circuit and be introduced into the patient.
A still further drawback of traditional CPB circuits relates to their physical location within the operating room. Once again, due to their bulky nature and nonconsolidated layout, traditional CPB circuits are disposed well outside the sterile surgical field. Positioning the CPB circuit in this fashion requires the use of long lengths of surgical tubing to connect the patient to the CPB circuit. This increases the blood""s exposure to foreign substances, well known to activate a system wide roster of plasma proteins and blood components designed to act locally in response to infection or injury.
A need exists for apparatus systems, methods and associated equipment to minimize and/or eliminate the aforementioned drawbacks of traditional CPB circuits. The present invention is directed at addressing this need.
The present invention solves the aforementioned drawbacks of the prior art by providing a cardiopulmonary bypass integration panel (xe2x80x9cCPB integration panelxe2x80x9d) which consolidates and miniaturizes the complete CPB circuit such that it may be positioned within (or closely adjacent to) the sterile field. The CPB integration panel of the present invention may take the form of a panel, manifold or box-type structure designed to support or enclose one or more elements of the CPB circuit. These elements may include, but are not necessarily limited to, a blood pump, a cardioplegia pump, an oxygenator, a heat exchanger, venous and/or arterial reservoirs, and an arterial filter. The majority of these components are miniaturized relative to prior art offerings, including but not limited to the blood pump, the oxygenator, and the heat exchanger. One such miniaturized oxygenator, incorporating blood pump features, forms part of the present invention. The oxygenator of the present invention improves upon the prior art by decreasing the priming volume and utilizing less fiber to obtain proper oxygenation. Further, the oxygenator of the present invention provides a novel flow path, whereby the size of the oxygenator may be reduced without decreasing functionality of the oxygenator.
Component modularity is maintained for ease of component replacement should the need arise, such as by equipping the circuit components with quick-connect couplings. Ease of use is also facilitated by providing quick-connect couplings to quickly and easily couple the CPB integration panel to the venous and arterial cannulae employed to transport blood between the patient and the CPB integration panel. The CPB integration panel may be positioned to define the sterile/non-sterile field. In this regard, the CPB integration panel may have a sterile field drape or other sterile/non-sterile barrier directly integrated/attached into its structure through standard methods. When configured as a manifold or box-type structure, the CPB integration panel may house within its structure the various fluid communication conduits that extend between elements of the CPB circuit. The CPB integration panel may mount on an IV (standardized or custom) pole, bed rail mounted pole, or rest within the surgical field (e.g. directly on the surgical bed).
A cable-driven blood pump is preferably employed as the means of distributing blood throughout the CPB integration panel. The CPB integration panel may also include a passive reservoir or an active reservoir on the venous side. The CPB integration panel may be pre-packaged for easy deployment, including the ability to ship the entire circuit, up to the sterile side cannula connections pre-primed. The CPB integration panel is also developed for ease of priming including a quick-purge (CO2 purge connection) and quick-prime (vacuum connection for easy circuit prime) latch connections which can be easily attached/detached.
By and through these features, the CPB integration panel of the present invention represents a significant advancement over traditional CPB circuits found in the prior art. First, the CPB integration panel of the present invention boasts a dramatically reduced prime-volume relative to traditional CPB circuits, thereby reducing hemodilution and its associated drawbacks. This is particularly advantageous in neonatal and pediatric cases, not to mention adult cases. The CPB integration panel of the present invention may also be positioned at a higher vertical level than the patient, thereby minimizing the risk of introducing air emboli into the patient. The CPB integration panel of the present invention minimizes the blood""s exposure to foreign surfaces, thereby reducing the risk of activating the blood""s immuno-response system.